Vacuum motor for clutches



Sept. 4, 195] Filed Oct. 16, 1944 T. H. THOMAS VACUUM MOTOR FOR CLUTCHES 3 Sheets-Sheet 1 JNVENTQ)? 7/VaMAs H 72mm T. H. THOMAS Sept. 4, 1951 VACUUM MOTOR FOR CLUTCHES 5 Sheets-Sheet 2 Filed Oct. 16, 1944 INVENTOR. 77mm? HI Wow/1.5

BY J J I if:

Sept. 4, 1951 T. H. THOMAS VACUUM MOTOR FOR CLUTCHES Fil ed Oct. 16, 1944 3 Sheets-Sheet 5 INVEN TOR. 7mm; h! THOMAS ATTORNEY Patented Sept; 4, 1951 UNITED STATES PATENT OFFICE 2,566,842 VACUUM MOTOR FOR CLUTCHES Thomas H. Thomas, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application October 16, 1944, Serial No. 558,841

1 Claim.

This invention relates in general to the clutch mechanism of an automotive vehicle and in particular to power means for controlling the operation thereof.

More specifically, the invention relates to a pressure differential operated power means for controlling the operation of a combined centrifugal and spring operated clutch. To this end there is suggested a manifold vacuum operated motor operably connected to the spring operated pressure plate of the clutch, said plate having mounted thereon centrifugally operated means supplemented by the operation of the clutch springs in effecting the desired smooth engagement of the clutch.

A further feature of the invention relates to the provision of power means for controlling the operation of the aforementioned combined centrifugal and spring operated clutch, said means being controlled in part by the means for operating the engine throttle of the vehicle: apropos the latter feature of the invention it is an object to so correlate the opening of the throttle and the clutch engaging operation of the power means as to insure an effective operation of the centrifugal means in engaging the clutch.

A further object of the invention is to provide a pressure differential operated motor operable, in controlling the clutch engaging operation of a combined centrifugal and spring operated clutch mechanism, to effect two distinct stages of movement of the pressure plate, the first stage being relatively rapid and terminating when the driving and driven clutch elements are to a slight degree loaded by the spring means of the clutch, and the latter stage being relatively slow to effect, under unusual driving conditions, an operation of the clutch springs to supplement the clutch en aging action 01' the centrifugally operated weights.

Yet another object of the invention is to so construct and arrange the parts of the aforementioned mechanism as to correlate the timing of the operation of the centrifugal mechanism with respect to the timing of the operation of the clutch springs to the end that under ordinary driving conditions the clutch will be engaged by the action of the centrifugal mechanism and to a degree by the clutch springs, the clutch springs, after a certain opening of the throttle to reduce the manifold vacuum, supplementing the centrifugal mechanism in completing the engageporarily subject to a heavy torque for example 2 when the car, heavily loaded, is going up an incline.

Yet another object of my invention is to provide power means for quickly and completely disengaging a combined centrifugal and spring operated friction clutch; for with a conventional type of centrifugal clutch the disengagement thereof is delayed, resulting in a slipping of the clutch and an undesired deceleration of the vehicle, when the accelerator is released and the car is travelling at a relatively high speed. With my invention, however, that is the; combination of centrifugally operated means and spring operating power means for effecting the disengagement and controlling the engagement of the clutch plates, there is a complete separation of said plates immediately after control means, for example the accelerator and either a governor or transmission controlling shift lever, is operated to effect a clutch disengaging operation of the power means.

In general therefore it is the object of the invention to provide an automatically operable friction clutch structure operative to accurately simulate a skillful manual operation of said clutch to the end that the vehicle may be effectively accelerated under all conditions of service.

Other objects of the invention and desirable details of construction and combinations of parts will be apparent from the following description of a preferred embodiment of the invention, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a diagrammatic view of the clutch operating mechanism constituting the present invention;

Figure 2 is a sectional view disclosing in detail the structure of the combined centrifugal and spring operated clutch to be controlled;

Figure 3 is a fragmentary view disclosing a portion of the connection interconnecting the clutch, the clutch motor and the clutch pedal;

Figure '4 is an enlarged fragmentary and sectional view of a portion of the clutch structure of Figure 2 disclosing the clutch engaging springs; Figure 5 is a diagrammatic view, largely in section disclosing the relative position of the parts of the mechanism when the clutch plates are slightly loaded by the clutch springs of the mechanism and just prior to the clutch engaging operation of the centrifugal weights of said mechanism.

In that embodiment of the invention selected for illustration there is diagrammatically disclosed in Figure 1 a clutch mechanism III which is adapted to interconnect the internal combustion engine I2 of an automotive vehicle with a conventional change-speed transmission [4, the latter being drivably' connected by a propeller shaft I8 with the driving wheels of the vehicle. The accelerator ll of the vehicle is connected to a throttle operating crank II by means of a link II, a lever I3 and a link II the latter being provided with a pin at its end fitting with a slotted portion'8 of the throttle operating crank I8 to provide a lost motion connection.

My invention is directed to power means for controlling the operation of the clutch I8, the latter being of a combined centrifugal and spring operated type. As disclosed in Figure 2, a flywheel 28, drivably connected with the engine I2, constitutes the driving element of the clutch;

and a disk 22, slidably keyed to the propeller shaft I6 at 24 and provided with friction rings 26 constitutes the driven clutch element. The means for forcing the driven clutch element into driving engagement with the driving clutch element comprises a pressure Plate 28, mounted within a cup shaped housing 38 secured to the flywheel plate by fastenings 32. A ring 34, mounted on the plate by a plurality of pins 36, constitutes, together with the plate, a pressure applying unit, said unit being normally urged to the left, to engage the clutch, by means of a plurality of angularly spaced clutch springs 38, Figure 4.

A plurality of angularly spaced centrifugally operated weight members 48 each having a leverlike shank portion 42 extending through the plate 28 in to engagement with the ring 34, cooperate with the clutch engaging action of the springs 38 at or above a predetermined R. P. M. of the flywheel, the centrifugal force developed by the rotating weights serving to urge the weights outwardly in direct proportion to the angular speed of the flywheel and tending to force the ring from the plate and into engagement with the driven clutch element 28. Above the predetermined R. P. M. of the flywheel the clutch engaging springs 38 are supplemented by the clutch engaging operation of the weights 48. Springs 44 sleeved over the pins 38 between the plate 28 and stops 48, serve as return springs to keep the plate and ring together when the flywheel is static or below the aforementioned critical angular speed. The loading of the clutch is thus the additive result of the effects of the clutch springs 38 and the centrifugally operated weights 48, the effect-of the latter being a variable the value of which is a function of the R. P. M. of the flywheel.

The invention is specifically directed to power operated means for controlling both the disengagement and engagement of the aforementioned clutch, and in such fashion as to result in its most eifective operation under various conditions of service of the vehicle. The above described specific clutch structure is not claimed herein.

To the above end there is provided a fluid pressure operated motor preferably a doubleended manifold vacuum operated motor 48 comprising a cylinder 58, pivotally secured to the chassis of the vehicle at 82, and a reciprocable piston element 54, the latter being operably connected to the pressure plate 28- of the'pressure unit by a rod 88, crank 58, slidable collar 68, lever operating finger members-82 and pins 64. The finger members 82 are fulcrumed intermediate their ends upon pins 88, secured to the housing member 38. The pressure plate may also be operated to disengage the clutch by means of a conventional clutch pedal 88 interconnected with the sleeve 68 by. linkage I8. A spring II serves to maintain the pedal 68 in its oil position against a stop II the pedal being then in its clutch engaged position.

One of the most important features of my in- .vention resides in the valvular mechanism for controlling the operation of the aforementioned clutch operating motor. To this end there is provided a three-way valve I2 of conventional design disclosed in detail in Figure 6, said valve being operated by a solenoid I4 to open the valve thereby connecting a compartment I6 of the motor 48 with the intake manifold I8 of the engine I2 via a conduit 88, valve 12, and a fitting 82, Figure 5. A closing of the valve I2 serves to vent the compartment 18 tothe atmosphere via an air cleaner 84, the valve I2 and the flttting 82. Describing the valve I2 in greater detail an energization of the solenoid I4 serves to open the valve, that is move a valve member 88 to a seat I3, Figure 6, thereby interconnecting the intake manifold I8 with the motor compartment I6; and a de-energization of the solenoid I2 results in a closing of the valve, a spring I5 operating to seat the valve member 88 on a seat I1 ing wheel 88 of the vehicle. As disclosed in Figure 1 the grounded governor operated switch 88 is wired in series with the solenoid I4 and the accelerator operated switch 86 the latter switch being wired to a grounded battery 88. A cut out switch I88 and the ignition switch I82 of the ignition system of the vehicle are interposed in series in the wiring interconnecting the battery and accelerator operated switch. The governor operated switch 88 is closed when the vehicle is at a standstill or is travelling at or below a certain relatively low speed; and the accelerator operated switch 88 is closed when the accelerator is released.

Describing now the shift lever operated mechanism for operating the switches 88 and 82 the shift lever 84 is preferably connected with said switches and shift rail actuating cranks I8 and 2| by the force transmitting links and levers disclosed in Figure 1. Describing the operation of this force transmitting means and the parts thereof a spring 23, interposed between a stop 25 fixedly secured to the steering post 21 of the vehicle and a stop 28 fixedly secured to a shaft 3|, serves to bias said rod downwardly to the position disclosed in Figure 1. Now to the lower end of the rod 3| there is fixedly secured a crank 33 through which extends a pin 35; and when said rod is moved downwardly by the spring 28 one end of said pin extends within an opening 31 in a floating crank 39. To one end of the crank 38 there is pivotally connected a rod 4I said rod being pivotally connected at its other end to the end of the crank I8. This crank when rotated clockwise serves to actuate other force transmitting means .within the casing of the three speeds forward and reverse transmission I4 to establish. the transmission in its high gear setting; when said crank is rotated countarconnection between the crank 2| and the shift lever 94 includes a link 43 pivotally connected The valve I4 is then-closed by the expansion of the valve spring I5 and this operation results in a de-energization of the motor 48 to initiate a re-engagement of the clutch.

There is thus provided, by the above described shift lever operated switch operating mechanism, means, cooperating with the accelerator operated switch 36, for effecting a clutch disengaging opto a floating crank 45 said crank being rotatably mounted on the shaft 3| which is bodily movable through said crank. This crank is provided with an opening 41 to receive one end of the pin 35.

When the-driver wishes to establish the transmission in its second gear setting he rotates the shift lever 94 counterclockwise and this operation serves to rotate the floating crank 39. Now the switch 92 is preferably so constructed that the force necessary to close the same, that is the force necessary to compress a spring within the switch connected to its movable contact, is less than the force necessary to effect the initial movement of the high second shift rail. It follows therefore that the initial movement of the shift lever 94 results in a pivoting of the crank 39 about its connection with the rod 4|; and this operation results in a closing of the clutch controlling switch 92. Continued movement of the shift lever, that is the movement after the switch 92 is closed and there is no possible further movement of a link 49 interconnecting the crank 39 with said switch, results in a pivoting of said crank about its pivotal connection with the link 49; and this operation results in the operation of the transmission to establish the same in its second gear setting. After this setting is established the driver removes his hand from the shift lever whereupon the aforementioned spring within the switch 92 operates to open said switch. This switch is so constructed that the same is also closed when the driver moves the shift lever 94 to establish the transmission in its high gear setting; and the spring means within said switch also functions to open the same when the high gear setting of the transmission has been established and the driver removes his hand from the shift lever.

Describing the operation of the switch mechanism to establish the transmission in either reverse gear or low gear the driver first rotates the shift lever 94 upwardly in a plane perpendicular to the plane of the steering wheel 96; and this operation serves to bodily move the shaft 3| upwardly against the tension of the spring 23. The upper end of the pin 35 is by this operation moved into the opening 41 and a subsequent rotation of the shift lever, either to establish the transmission in reverse or low gear, results in a rotation of the cranks 45 and 2| to effect one or the other of these settings of the transmission. The shaft 3| is provided with a recessed portion 5| which receives a pin 53 operably connected to the grounded switch 99; and as will be obvious from an inspection of Figure 1 when the shaft 3| is moved upwardly, in the operation of establishing the transmission in either reverse or low gear, the switch 90 is closed by virtue of the forcing of the pin 53 to the left, Figure 1, when the end of said pin is forced out of the recess 5| and onto the full bodied portion of the shaft. After the clutch has been disengaged and eration of the motor I0 during the first increment of movement of the shift lever as it is moved to establish the transmission in any oneof its four gear settings. The parts of the mechanism are preferably so constructed and arranged that the clutch is disengaged before the transmission I is operated. It is to be noted that the switch operating force transmitting means of my invention is such as to effect a closing of the switch mechanism when the shift lever is moved in either one of two different planes. The clutch control mechanism of my invention may be in corporated in the power plant of a vehicle which includes a so-called kickdown type of selective gear transmission of the day that is a transmission which may, by a manual operation of a shift lever, be established in any one of a plurality of forward gear settings or a reverse gear setting; and after a forward gear setting is established than a vacuum and spring operated kickdown motor unit, controlled by a vehicle speed responsive governor and the accelerator of the vehicle, takes over the operation of said transmission. In this type of well known transmission mechanism incorporated on cars now in operation, the kickdown on downshift operation of the motor unit is facilitated by a momentary disabling of the ignition system of the engine; and the power plant including such a mechanism may aso include a fluid coupling.

Referring now to Figure 5 disclosing the motor 48 and valvular means for controlling said motor there is provided valvular means for effecting a two-stage clutch engaging operation of said motor. The so-called first stage valve of said valvular means comprises a hub portion I04 of an end plate I06 of the motor which hub portion cooperates with a slot I08 in the connecting rod 56 interconnecting the piston 54 with the clutch operating crank 58. The so-called second stage valve of the valvular means comprises a seat III) of aported portion of the end plate I06 and a valve member ||2 adapted to cover or uncover the outer end of a port H4. The valve member H2 is actuated by a rod IIB which is connected rt its outer end to the central portion of a diaphragm |I8 secured to the end of a hollow boss I20 extending from the end plate. This boss, together with the diaphragm II8, a portion of the end plate and a partition I22 within the boss, outline compartments I24 and I26. The boss is ported at I28 and I39 the latter port receiving a conduit I32 which is connected at its.other the transmission established in gear, a release of the shift lever, by the removal of the hand therefrom, results in an expansion of the spring 23 to open the switch 90; and this operation results in a de-energization of the solenoid I2.

end to the conduit 89. A plate I33, ported at I35, ma be provided to protect the diaphragm from foreign matter. A spring I34, interposed between the partition I22 and the diaphragm H8 and sleeved over the rod I I6, serves to bias the valve member II2 to a position to uncover the port II4 thereby venting a compartment I36 of the motor 48 to the atmosphere via the port II4, compartment I24 and the port I28. The outer end of the boss I29 together with the diaphragm I I8, the partition I22, the spring I34, the rod I I6 and the plate I33 constitute power means for operating the valve member 2; for taken together they go to make up a spring and pressure differential operated motor unit.

Describing now the operation of the clutch controlling mechanism constituting. my invention, with the accelerator released and the vehicle at a standstill the governor operated and accelerator operated switches 88 and 86 are closed accordingly the solenoid I4 is energized to open the three-way valve I2. However the gaseous pressure within the intake manifold is at this time equal to the pressure of the atmosphere accordingly the motor 48 is not energized.

Now when the engine is started the intake manifold is immediately partially evacuated by virtue of the pumping action of the engine pis-' tons accordingly the compartment 16 of the motor 48 is also partially evacuated; and this results in a movement of the piston 54 to the left, Figure 5, to effect a movement of the pressure plate of the clutch away from the driven clutch plate. This movement of the piston is effected inasmuch as the same is then subjected to a differential of pressures the compartment I36 of the motor being maintained at atmospheric pressure by virtue of the operation of a check valve I38 mounted in the end plate I06 of the motor.

The driver will then probably establish the transmission in its low gear setting by an operation of the shift lever 94 and after this operation is effected he will then depress the accelerator to effect an engagement of the clutch to get the car under way. Describing the clutch engaging operation of the motor 48 the first increment of movement of the accelerator serves to open the switch 86; and the construction and arrangement of the parts of the mechanism, particularly the construction of the lost motion connection 9, is such that said switch is opened before the throttle is opened. Now with the opening of the switch 86 the solenoid I4 is deenergized thereby permitting the spring numeral I within the valve I2 to close said valve, that is. effect a venting of the compartment 16 to the atmosphere; and when said compartment is vented to the atmosphere this operation initiates a clutch engaging movement of the piston 54 under the action of the several clutch springs 38. The piston is then moved to the right Figure 5, the air in the compartment I36 being pushed out of said compartment via the slot I08 in the connecting rod 56.

When the piston has moved a certain distance to the right the slot is covered by the hub portion I04 all as disclosed in Figure 5, whereupon the piston either comes to a stop or its rate of movement is at least reduced the operation effected being dependent upon the mode of operation of the accelerator. Now the length of the slot I08 is so determined and the remainder of the parts of the mechanism are so constructed and arranged that this first stage operation of the valve means is completed when the pressure plate of the clutch has moved sufllciently to effect a slight loading of the driving and driven clutch plates; and this operation is effected before or at substantially the same instant that the opening movement of the throttle is initiated. It follows therefore that the clutch plates are to a degree loaded by the clutch springs 38 when the operation of the centrifugally operated weights is initiated. If at this time the R. P. M. of the engine is not high enough to effect a clutch engaging operation of the centrifugal weights then the clutch springs 38 serve,

. if the vehicle load is not too high. to insure a III sufilcient engagement of the clutch to effect a forward motion of the vehicle.

The driver, in his operation of the accelerator, usually does not arrest the throttle opening movement of said control means accordingly continued depression 01' the accelerator will serve to open the throttle to speed up the engine; and when the R. P. M. of the engine is above a critical factor, which is of course relatively low, then the centrifugal weights 40 function to load the ring 34 of the pressure plate unit to effect the engagement of the clutch. Now when the motor is idling, that is before the above described first stage operation of the valve mechanism is completed, the degree of vacuum in the intake manitold is appreciably high accordingly the compartment I26 of the second stage valve means, which compartment is connected to the intake manifold, is evacuated to the same degree as the evacuation of said manifold. The differential of pressures acting on the diaphragm II8 therefore serves to overcome the spring I34 and maintain the valve member II2 seated, that is maintain the second stage valve closed until the throttle is sufllciently opened to lower the degree of vacuum in the intake manifold; and this usually occurs very shortly after the first stage operation of the valve mechanism is completed.

When the throttle is sufficiently opened to lower the vacuum in the intake manifold to a certainfactor then the gaseous pressure in the chamber I26 is increased and the spring I34 functions to open the second stage valve III. Air then passes from the motor compartment I36, via the port II4, chamber I24 and port I28, into the atmosphere and the clutch engaging movement of the piston is either resumed or continued, depending upon the previous mode of operation of the accelerator. The piston 54, in this second stage movement moves at a constant or substantially constant but relatively low rate of speed inasmuch as the rate at which the air is forced from the motor chamber I36 is relatively low. This rate of course may be varied by changing the size of the port I28.

There is thus provided a clutch mechanism which insures a smooth start of the vehicle from rest the clutch springs 38 supplementing the clutch engaging operation of the weights 40. If the vehicle is perchance heavily loaded then the engine will probably be slowed down in getting the vehicle under way; and this so-called laboring of the engine results in a slipping clutch inasmuch as the weights 40 exert a clutch engaging force which is directly proportional to the speed of the engine. The clutch springs 30 however come into action with the above decribed second stage operation of the motor 48 t supplement the operation of the weights thereby insuring suflficient loading of the clutch plates to prevent their slipping.

The vehicle being then under way the driver will release the accelerator and then operate the shift lever 94 to establish the transmission in a higher gear ratio setting. As described above the first increment of movement of the shift lever serves to close one or the other of the switches or 92 depending of course upon the operation of said lever. The accelerator being at the time released to close the switch 86 it follows that the motor 48 is again energized to eifect a disengagement of the clutch mechanism, all as previously described. After the operation of the transmission is completed the driver removes his hand from the shift lever thereby opening one or the other 01' the switches 90 or 92 to thereby effect an operation of the three-way valve 12 and initiate the above described clutch engaging operation of the motor 48. Subsequent depression of the accelerator will then, as described above, effect the second stage clutch engaging operation of the motor 48.

When the vehicle is slowed down below a certain speed then the governor operated switch 88 is closed and, if the accelerator is at the time released to close the switch 88, then the motor 48 is again energized to effect a disengagement of the clutch mechanism.

There is thus provided means, including the clutch springs 38 and the motor 48 for operating the same, for supplementing the clutch engaging operation of the centrifugal weights to insure the desired acceleration of the vehicle and prevent the clutch plate wearing effect of a slipping clutch when the engine is laboring. It is also to be noted that the motor 48 serves to insure a disengagement of the centrifugal clutch means, and thereby obviate any undesirable deceleration of the vehicle. when the accelerator is suddenly released when the vehicle is travelling at a relatively high speed.

While one illustrative embodiment has been described, it is not my intention to limit the scope of the invention to that particular embodiment, or otherwise than by the terms of the appended claim.

I claim:

A pressure differential operated motor adapted for use in a mechanism for actuating the friction clutch of an automotive vehicle, said motor including a double ended casing, one of the ends of the casing being provided with a port, valve means associated with said port and operative to control the flow of power fluid to and from the motor, the other end of the casing being provided with two ports operative to control the egress of power fluid from the motor, a power element housed within said casing said element, together with the casing, providing two power fluid receiving motor compartments, a spring loaded valve member cooperating with one of the aforementioned two ports to provide a check valve serving as part of means for controlling the REFERENCES CITED The following references are of record in the file of this patent:

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